Easy Deployed Distributed Acoustic Sensing System for Leakage Detection in Gas Pipelines

Abstract

This study focuses on Distributed-Fiber-Optic-Sensing (DFOS) technology, a cutting-edge approach for monitoring the integrity of oil and gas pipelines. Unlike traditional inspection methods, DFOS offers continuous, real-time monitoring capabilities, allowing for early detection and response to potential leaks, which is especially crucial in remote or inaccessible locations. The current study investigates the innovative and practical use of this technology through the internal deployment of fiber-optic cables within the pipeline for gas leak detection. To conduct our research, we used a standard industry pipe measuring 21 meters in length with a 4-inch internal diameter. The pipeline included a 1-meter section in the middle specifically designed for adaptability to various experimental setups. We tested the system at five different standard gas velocities (2, 6, 10, 14, and 18 m/s) and introduced leaks at the center of 1-m middle section in four sizes (¼", ½", ¾", and 1") at three different orientations (top, bottom, side). Our experimental setup is equipped with four distinct fiber-optic cable deployment methods: one external cable taped to the top of the pipeline, and three different cable types deployed internally. Our baseline experiment, conducted without any leaks, served as a reference to compare against the leak scenarios. We observed significant vibration anomalies at the leak locations, enabling us to not only detect but also accurately locate the leaks. The experiments revealed that leaks became more detectable as the size of the hole increased or as the velocity of the gas increased. Notably, the internal cables interacting with the flow, particularly the softer and lighter ones, displayed a higher sensitivity to these anomalies compared to the heavier cable, suggesting that the physical properties of the cables play a crucial role in detection capabilities. The leakage position also impacts detectability, being more detectable as it is closer to the cables. The external straight cable can also detect the leakage but is less sensitive compared to the internal light cables. The detectability of the external cable could be impacted by the coupling; improved coupling between the cable and the pipe can enhance its detectability of pipeline leakage. The principal innovation of our study lies in the internal deployment of fiber-optic cables for detecting pipeline leaks. This method represents a significant shift from traditional external deployment methods, offering a more field-practical and efficient solution for pipeline integrity monitoring. By providing real-time data on the state of the pipeline from within, this approach could dramatically improve the industry’s ability to prevent leaks and respond to incidents, thereby enhancing safety and operational reliability.